Generally, a muscle protein of meat is denatured by heat, thereby usually posing various problems, including dripping, grilling shrinkage, dryness in texture and toughness. Although these changes by heating bring out the inherently good taste of meat and make the meat more palatable on one hand, they on the other hand cause meat processing-related problems, including giving considerably poorer appearance, toughened texture, dry texture by the loss of juiciness, and decreased yield. These problems are more markedly notable in fried foods and pressure- and heat-sterilized foods, which have undergone stringent heating conditions, causing undesirable phenomena, such as yield reduction and breakdown of meat tissues. In addition, in processed foods using ground meat, so called "oil dripping" or "water release" occurs in which an animal fat, i.e., lard, contained in, or added to, raw material meat melts and flows out during heating.
Generally, a majority of the raw materials which can be used in such processed meat foods are frozen meat. When stored under freezing conditions in a long term, the water binding capacity of meat is decreased, so that the above-described problems incurred in meat processing become more markedly notable.
Conventionally, polymerized phosphates or saccharides have been added for improvement of the water binding capacity of frozen meat. However, since such substances must be added in large amounts to obtain sufficient effects, there arise the problems of drastically deteriorated flavor and texture of processed meat foods. Many of the currently generally produced processed meat foods, such as ham and sausages, are widely supplemented with protein materials, such as vegetable proteins, egg proteins, milk proteins and blood proteins, and mucopolysaccharides, such as carrageenan and gelatin, as binders for the purpose of improving bindability, water binding capacity, and yield. These binders, together with polymerized phosphates as curing agents, are added to meat to improve its water binding capacity and increase its yield. However, its texture is such that the meat is plainly chewy, losing the fibrous texture of meat and juiciness (meat texture).
In addition, although thermally coagulating proteins, such as egg albumen powder and soybean protein, and polysaccharides having gelation properties, such as carrageenan and gelatin, have water binding capacity in themselves, when added to the frozen meat of which the water binding capacity is once decreased, the decreased water binding capacity of frozen meat cannot be improved to the pre-freezing level without decreasing its flavor and texture.
Conventionally, as methods of suppressing a decrease in texture of meat which can be used in pressure- and heat-cooked foods, there have been disclosed some methods including a method comprising treating raw material meat with an animal protein, such as gelatin, albumin or casein (Japanese Patent Laid-Open No. Hei 5-64567); a method comprising adding a mucopolysaccharide other than animal proteins, such as guar gum, xanthan gum or carrageenan to raw material meat (Japanese Patent Laid-Open No. Hei 9-51757); and a method comprising immersing meat in a calcium-containing solution and a polymerized phosphate-containing solution as pretreatments, and then subjecting the treated meat to a heat-and-pressure treatment (Japanese Patent Laid-Open No. Hei 4-341160).
Although the method of adding an animal protein is effective in suppressing the amount of dripping formed upon pressure- and heat-sterilization of meat, the method is undesirable because of toughened texture or uniform texture without the texture inherently owned by the meat. Although the method of adding a mucopolysaccharide is effective in tenderizing the meat and suppressing its breakdown, the method gives rise to tacky texture after pressurization and heating. The method of adding a calcium solution or polymerized phosphate has a defect in that the meat gets a flexible, uniform, ham-like texture, thereby losing the texture of inherently owned by the meat, and none of these conventional methods can sufficiently satisfy in the improvements of the texture of meat after pressure- and heat-sterilization.
An object of the present invention is to provide a meat quality-improving agent for improving the water binding capacity of meat, particularly meat of which its water binding capacity is once lowered by storing under freezing and meat to be subjected to pressure- and heat-sterilized treatment, for improving the texture of the meat, and for suppressing meat shrinkage upon grilling of the meat.
Another object of the present invention is to provide a method for improving meat characterized by using the above meat quality-improving agent.
These and other objects of the present invention will be apparent from the following description.